| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | January 5, 1999 |
| PATENT TITLE |
Organo-Lewis acid as cocatalyst for cationic homogeneous Ziegler-Natta olefin polymerizations |
| PATENT ABSTRACT | A cationic metallocene complex with trisperfluorobiphenyl borate for use as a polymerization catalyst |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | February 18, 1997 |
| PATENT REFERENCES CITED |
Marks, Tobin J., Surface-Bound Metal Hydrocarbyls. Organometallic Connections between Heterogeneous and Homogeneous Catalysts, Accounts of Chemical Research, vol. 25, No. 2, pp. 57-65, Feb., 1992. Yang et al., Cationic Zirconocene Olefin Polymerization Catalysts Based on the Organo-Lewis Acid Tris(pentafluorophenyl)borane. A Synthetic, Structural, Solution Dynamic, and Polymerization Catalytic Study, J. Am. Chem. Soc., 116, 10015-10031, 1994 |
| PATENT GOVERNMENT INTERESTS | This invention was made with Government support under Contract No. DE-FG02-86ER13511 awarded by the Department of Energy. The Government has certain rights in this invention |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A catalytic complex of the formula: (CpCp'MR).sup.+ (RBR'R".sub.2).sup.- where Cp and Cp' is each C.sub.5 H.sub.n R.sub.5-n (n is 0-5), indenyl, allyl, benzyl, or C.sub.5 H.sub.n R.sub.4-n XNR (n is 0-4); M is Th, Zr, Hf, Ti, or U; X is R.sub.2 '"Si, where R'" is an alkyrl (C.ltoreq.10) or aryl group (C.ltoreq.10); R and R'" is each alkyl (C.ltoreq.20), benzyl (C.ltoreq.20), aryl (C.ltoreq.20), hydride, or silyl; B is Boron; R' is a fluorinated biphenyl; and R" is a fluaorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic fused ring group. 2. The complex of claim 1 wherein said polycyclic fused ring groups are naphthyl, anthryl, or fluorenyl. 3. A method of preparing a catalyst includig the step of adding a compound of the formula CpCp' MRR', where Cp and Cp' is each C.sub.5 H.sub.n R.sub.5-n, (n is 0-5) indenyl, allyl, benzyl, or C.sub.5 H.sub.n R.sub.4-n XNR (n is 0-4); M is Ti, Zr, Hf, Th or U; X is R.sup.2 " Si where R" is an alkyl (C.ltoreq.10) or aryl group (C.ltoreq.10); and R and R' is each alyl (C.ltoreq.10), benzyl (C.ltoreq.20), aryl (C.ltoreq.20), hydride or silyl; to perfluorobiphenyl borane in a nonpolar solvent. 4. The method of claim 3 wherein the solvent is selected from the group consisting of benzene, toluene, pentane and other non-polar solvents. 5. The method of claim 3 wherein said catalyst is prepared at -78.degree. C. 6. The method of claim 3 wherein said catalyst is prepared at room temperature. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION This invention relates to the compositions of matter useful as catalysts, to a method for preparing these catalysts and to a method for polymerization utilizing the catalysts. The use of soluble Ziegler-Natta type catalysts in the polymerization of olefins is well known in the prior art. In general, such systems include a Group IV-B metal compound and a metal or metalloid alkyl cocatalyst, such as aluminum alkyl cocatalyst. More broadly, it may be said to include a mixture of a Group I-III metal alkyl and a transition metal complex from Group IVB-VB metals, particularly titanium, zirconium, or hafnium with aluminum alkyl cocatalysts. First generation cocatalyst systems for homogeneous metallocene Ziegler-Natta olefin polymerization, alkylaluminum chlorides (AIR.sub.2 Cl), exhibit low ethylene polymerization activity levels and no propylene polymerization activity. Second generation cocatalyst systems, utilizing methyl aluminoxane (MAO), raise activities by several orders of magnitude. In practice however, a large stoichiometric excess of MAO over catalyst ranging from several hundred to ten thousand must be employed to have good activities and stereoselectivities. Moreover, it has not been possible to isolate characterizable metallocene active species using MAO. The third generation of cocatalyst, B(C.sub.6 F.sub.5).sub.3, proves to be far more efficient while utilizing a 1:1 catalyst-cocatalyst ratio. Although active catalyst species generated with B(C.sub.6 F.sub.5).sub.3 are isolable and characterizable, the anion MeB(C.sub.6 F.sub.5).sub.3.sup.- formed after Me.sup.- abstraction from metallocene dimethyl complexes is weally coordinated to the electron-deficient metal center, thus resulting in a drop of certain catalytic activities. The recently developed B(C.sub.6 F.sub.5).sub.4.sup.- type of non-coordinating anion exhibits some of the highest reported catalytic activities, but such catalysts have proven difficult to obtain in the pure state due to poor thermal stability and poor crystallizability, which is crucial for long-lived catalysts and for understanding the role of true catalytic species in the catalysis for the future catalyst design. Synthetically, it also takes two more steps to prepare such an anion than for the neutral organo-Lewis acid. SUMMARY OF THE INVENTION Accordingly, it is an object of the subject invention to prepare and utilize a new class of olefin polymerization catalysts. A further object of the subject invention is a catalyst which permits better control over molecular weight, molecular distribution, stereoselectivity, and comonomer incorporation. Another object of the subject invention is a Ziegler-Natta type catalyst system which reduces the use of excess cocatalyst and activates previously unresponsive metallocenes. These and other objects are attained by the subject invention whereby in one embodiment, a strong organo-Lewis acid, such as perfluorobiphenylborane (PBB) is utilized as a highly efficient cocatalyst for metallocene-mediated olefin polymerization and as a catalyst for a ring opening polymerization of THF. PBB can be synthesized in much higher yield than B(C.sub.6 F.sub.5).sub.3 and the anion generated with PBB is non-coordinating instead of weakly coordinating as in the case of B(C.sub.6 F.sub.5).sub.3. Thus, the former exhibits higher catalytic activities and can activate previously unresponsive metallocenes. The catalytically active species generated with PBB are isolable, X-ray ciystallographically characterizable instead of the unstable, oily residues often resulting in the case of B(C.sub.6 F,).sub.4.sup.-. In addition, PBB exhibits even higher catalytic activities in most cases. In one embodiment of the subject invention a strong organo-Lewis acid, such as perfluorobiphenylborane (PBB), is utilized to synthesize stoichiometrically precise, isolable/crystallographically characterizable, highly active "cation-like" metallocene polymerization catalysts. The biphenyl groups of PBB may be connected to the Boron at the meta, para, or ortho position. PPB reacts with early transition metal or actinide alkyls to yield highly reactive cationic complexes: (CpCp'MR).sup.+ (RBR'R".sup.-.sub.2).sup.-. where CpCp'=C.sub.5 H.sub.n R.sub.5n (n is 0-5), indenyl, allyl, benzyl, C.sub.5 H.sub.n R.sub.4-n XNR (n is 0-4) M=early transition metal or actinide, e.g., Ti, Zr, Hf, Th, U; X=R.sub.2 '"Si, where R'" is an alkyl or aryl group (C.ltoreq.10) R, R'"=alkyl, benzyl, or aryl group (C.ltoreq.20), hydride, silyl; B =Boron R'=fluorinated biphenyl R"=fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic fused rings such as naphthyl, anthryl, or fluorenyl As a specific example of the above, the reaction of PBB with a variety of zirconocene dimethyl complexes proceeds rapidly and quantitatively to yield, after recrystallization from hydrocarbon solvents, the catalytic complex of Eq. 1. ##STR1## Such catalytic complexes have been found to be active homogeneous catalysts for c-olefin polymerization and, more particularly, the polymerization, copolymerization or oligopolymerization of ethylene, .alpha.-olefins, dienes and acetylenic monomers, as well as intramolecular C-H activation. The cocatalyst of the subject invention may be referred to as BR'R", where B =Boron; R' and R" represent at least one and maybe more fluorinated biphenyls or other polycyclic groups, such as naphthyl. Two of the biphenyls may be substituted with a phenyl group. Both the biphenyls and the phenyl groups should be highly fluorinated, preferably with only one or two hydrogens on a group, and most preferably, as in PBB with no hydrogens and all fluorines. The cocatalyst system of the subject invention can be better understood with reference to the drawings wherein: FIG. 1 is a structural depiction of PBB; FIG. 2 is a reaction pathway for the synthesis of PBB; FIG. 3 shows the reaction pathway for a catalyst system according to the subject invention; FIG. 4 shows the reaction pathway for a second catalyst system according to the subject invention; FIG. 5 shows the reaction pathway for a third catalyst system according to the subject invention; and FIG. 6 shows the reaction pathway for a fourth catalyst system according to the subject invention. DETAILED DESCRIPTION OF THE INVENTION The reaction of perfluorobiphenylborane with a variety of zirconocene and other actinide or transition metal dimethyl complexes proceeds rapidly and quantitatively at room temperature in noncoordinating solvents to yield, after recrystallization, complexes. This catalytic reaction may be used in the polymerization, copolymerization, oligomerization and dimerization of .alpha.-olefins. In addition, the catalyst of the subject invention may be used as a cocatalyst in conjunction with aluminum alkyls, aluminum aryls, (AlR3, R=Et, Me, Ph, naphthyl) or methyl alumoxane (Al(CH.sub.3)O).sub.n for increased polymer yields. PBB (FIG. 1) has been synthesized in quantitative yields of 91 % as compared to the 30-50% yields experienced with B(C.sub.6 F.sub.5).sub.3, currently a very important Lewis acidic cocatalyst in industry (FIG. 2). The Lewis acidity of PBB has been shown to be much greater than that of B(C.sub.6 F.sub.5).sub.3 by comparative reactions of Cp*.sub.2 ThMe.sub.2 with B(C.sub.6 F.sub.5).sub.3 and PBB (Cp*=C.sub.5 Me.sub.5). The former reagent does not effect Me.sup.- abstraction, while the latter gives the catalyst shown in FIG. 3. The reaction of PBB with a bis-Cp type of dimethyl zirconocenes forms a dinuclear methyl-bridged zirconocene cation such as ##STR2## (1:1 or 2:1) where Cp=C.sub.5 H.sub.5 Cp=Cp.sub.5 H.sub.3 Me.sub.2 or Cp=C.sub.5 M.sub.5 and a hydride-bridged analog such as ##STR3## where Cp=C.sub.5 H.sub.5 or Cp=C.sub.5 H.sub.3 Me.sub.2 More particularly, reaction of PBB with group 4 and Th methyls proceeds cleanly to yield cationic complexes such as set forth below. ##STR4## For ethylene polymerization, catalytic activities of dinuclear cations generated from PBB are greater than those of monomeric cations generated from B(C.sub.6 F.sub.5).sub.3 presumably because (MePBB).sup.- is a non-coordinating anion as compared to the weakly coordinating anion MeB(C.sub.6 F.sub.5).sub.3. The dinuclear cations have also been found to catalyze the rapid ring-opening polymerization of THF to produce poly(tetrahydrofuran), an important thermoplastic elastomer and artificial leather. Monomeric zirconocene cations have also been generated in situ by the reaction of Cp.sub.2 ZrMe.sub.2 and PBB at 60.degree. C. ##STR5## These attempts show very high activities for olefin polymerization, and identify (MePBB).sup.- to be a truly non-coordinating anion. The polymerization data with metallocene cations having various anions are summarized in Table 1. TABLE 1 __________________________________________________________________________ Polymerization Data entry .mu.mol polymer M.sub.wd.sup.c no. catalyst of cat conditions monomer(s).sup.a yield (g) activity.sup.b (10.sup.-3) M.sub.w /M.sub.n remarks __________________________________________________________________________ 1. (Cp.sub.2 ZrMe).sub.2 Me.sup.+ 15 100 mL toluene ethylene .80 4.80 .times. 10.sup.6 559 3.06 MePBB.sup.- 25.degree. C., 40 s 2. Cp.sub.2 ZrMe.sup.+ 15 100 mL toluene ethylene 1.00 4.00 .times. 10.sup.6 124 2.03 MeB(C.sub.6 P.sub.5).sub.3.sup.- 25.degree. C., 60 s 3. (Cp".sub.2 ZrMe).sub.2 Me.sup.+ 15 100 mL toluene ethylene 1.30 7.80 .times. 10.sup.6 392 2.72 MePBB.sup.- 25.degree. C., 40 s 4. Cp".sub.2 ZrMe.sup.+ 15 100 mL toluene ethylene 1.50 6.00 .times. 10.sup.6 321 1.42 MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 60 s 5. (Cp.sub.2 ZrMe).sub.2 Me.sup.+ 15 100 mL toluene ethylene 1.07 4.30 .times. 10.sup.6 370 2.28 MePBB.sup.- 25.degree. C., 60 s 6. Cp.sub.2 ZrMe.sup.+ 15 100 mL toluene ethylene 0.80 3.20 .times. 10.sup.6 136 2.54 MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 60 s 7. CpTiMe.sup.+.sub.2 50 5 mL toluene styrene 0.35 1.61 .times. 10.sup.6 170 2.56 ›rrrr! > 98% MePBB.sup.- 25.degree. C., 15 min 8. CpZrMe.sup.+.sub.2 50 5 mL toluene styrene 1.45 1.00 .times. 10.sup.7 27.6 2.63 atactic MePBB.sup.- 25.degree. C., 10 min 9. CpHfMe.sup.+.sub.2 50 5 mL toluene styrene 0.69 3.17 .times. 10.sup.6 24.8 2.98 atactic MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 15 min 10. CpHfMe.sup.+.sub.2 50 5 mL toluene styrene 1.16 5.33 .times. 10.sup.6 22.9 2.78 atactic MePBB.sup.- 25.degree. C., 15 min CpTiMe.sup.+.sub.2 50 25 mL toluene ethylene 0.70 1.70 .times. 10.sup.5 848 23.7 39.5% hexene MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 5 min 1-hexene incorporation CpTiMe.sup.+.sub.2 50 25 mL toluene ethylene 4.51 1.08 .times. 10.sup.6 151 4.32 43.6% hexene MePBB.sup.- 25.degree. C., 5 min 1-hexene incorporation CGCZrMe.sup.+ 15 100 mL toluene ethylene 0 -- -- -- MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 20 min CGCZrMe.sup.+ 15 100 mL toluene ethylene 1.56 1.56 .times. 10.sup.6 7.69 2.78 MePBB.sup.- 25.degree. C., 4 min CGCTiMe.sup.+ 15 100 mL toluene ethylene 0.21 8.40 .times. 10.sup.4 1058 9.54 MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 10 min CGCTiMe.sup.+ 15 100 mL toluene ethylene 0.83 4.98 .times. 10.sup.6 305 2.56 MePBB.sup.- 25.degree. C., 40 s CGCZrMe.sup.+ 50 25 mL toluene ethylene 0 -- -- -- MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 15 min 1-hexene CGCZrMe.sup.+ 50 25 mL toluene ethylene 6.97 5.58 .times. 10.sup.5 10.0 2.68 33.6% hexene MePBB.sup.- 25.degree. C., 15 min 1-hexene incorporation CGCTiMe.sup.+ 25 25 mL toluene ethylene 0.05 1.20 .times. 10.sup.4 63.2% hexene MeB(C.sub.6 F.sub.5).sub.3.sup.- 25.degree. C., 10 min 1-hexene incorporation 20. CGCTiMe.sup.+ 25 25 mL toluene ethylene 1.95 4.68 .times. 10.sup.5 105 1.86 65.3% hexene MePBB.sup.- 25.degree. C., 10 min 1-hexene incorporation __________________________________________________________________________ .sup.a 1 atm ethylene pressure; 17.4 mmol of styrene, and 44.5 mmol of 1hexene. .sup.b g polymer/›(mol of cationic metallocene) .multidot. atm .multidot. h!, except in entries 7-10: polystyrene/›(mol catalyst) .multidot. (mol monomer) .multidot. h! (reproducibility between runs .apprxeq. 10.about.15%). .sup.c GPC relative to polystyrene standards. Other types of cationic metallocene catalyst systems can also be created with PBB. Metallocene cations of mono-Cp type (FIGS. 4 and 5) have been formed by the reaction of mono-pentamethyl Cp triethyl group IV complexes with and PBB. These are very good syndiospecific styrene polymerization catalysts (FIGS. 4 and 5). Constrined geometry types of zirconocene and titanocene cations such as those in FIG. 6 where m=Zr, Ti, are readily produced by thereaction of thecorresponding dimethyl metallocenes with PBB. They are highly naked cations and much moreactive catalysts than those generated with B(C.sub.6 F.sub.5).sub.3 |
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